Receptors for neurotransmitters require scaffolding proteins for membrane microdomain targeting and for regulating receptor function. Using a yeast two-hybrid screen, α-actinin-1, a major F-actin cross-linking protein, was identified as a binding partner for the C-terminal domain of metabotropic glutamate receptor type 5b (mGlu5b receptor). Co-expression, co-immunoprecipitation, and pull-down experiments showed a close and specific interaction between mGlu5b receptor and α-actinin-1 in both transfected HEK-293 cells and rat striatum. The interaction of α-actinin-1 with mGlu5b receptor modulated the cell surface expression of the receptor. This was dependent on the binding of α-actinin-1 to the actin cytoskeleton. In addition, the α-actinin-1/mGlu5b receptor interaction regulated receptor-mediated activation of the mitogen-activated protein kinase pathway. Together, these findings indicate that there is an α-actinin-1-dependent mGlu5b receptor association with the actin cytoskeleton modulating receptor cell surface expression and functioning.